This invention relates to a method of manufacturing a hydroxyapatite and an aqueous solution of biocompounds at the same time from tissue (vital tissue) by taking advantage of an electrochemical reaction. Hydroxyapatite is useful as toothpaste, biomaterials, cosmetics, etc., while an aqueous solution of tissue is useful as a natural medium.
Tissue is biologically synthesized by a living body by making use of bioelements. The tissue is formed of biodegradable materials which may be utilized as a nutrition for the species of other kind.
Specifically, this invention is related to a method wherein the biomaterials are to be obtained through the decomposition and separation of tissue by employing an electrochemical reaction in an aqueous solution instead of employing biodegradation, thereby making it possible to mass-produce various kinds of biomelecules concurrently and more cheaply as compared with the biodegradation.
This invention is further related to a method wherein tissue is separated as a biochemical raw material by a process similar to the carbonization of coal or petroleum refining where chemical raw materials are separated from natural resources. More specifically, this invention related to a method of dissolving and recrystallizing tissue by making use of an electrochemical reaction, thereby transforming the tissue into biochemical raw materials.
In particular, this invention related to a method wherein an aqueous solution of biocompounds and hydroxyapatite are to be simultaneously produced from tissue containing minerals, lipid, saccharides, protein, collagen, amino acid, nucleoside and hydroxyapatite.
More particularly, this invention related to a method of dissolving and recrystallizing biomaterials in an aqueous solution by making use of an electrode reaction in the aqueous solution without necessitating the employment of chemicals, thereby making it possible to simultaneously obtain, in large quantity, safely and cheaply, not only an aqueous solution of biocompounds including a small quantity of minerals, amino acid, nucleoside, collagen, lipid, saccharides and protein; but also hydroxyapatite containing minerals, protein, lipid, saccharides, collagen, amino acid and nucleoside.
Since peptide and hydroxyapatite can be incorporated in a tissue and are indispensable materials for the growth the tissue, the natural raw materials of them or the synthesized materials of them have been conventionally employed as a culture medium, as an artificial bone, as a raw material of bioceramics, etc.
According to the conventional method of transforming a waste tissue (a raw material) into useful resources such as peptide and hydroxyapatite, the waste tissue as a raw material has been subjected to treatments such as dissolution, extraction, baking, etc. in a specific manner depending on the kinds of compounds contained in the waste tissue, thereby transforming the waste tissue into useful resources.
For instance, peptide has been manufactured in such manners that a natural raw material (for example, protein) is decomposed using chemicals (such as HCl) into peptide, or a natural or synthesized raw material is subjected to a biotechnology using enzyme, whereby synthesizing peptide.
In the case of producing peptide by decomposing a natural raw material by making use of chemicals however, the decomposition reaction involved therein can be hardly controlled, thereby giving low yields of peptide even though a relatively large amount of peptide can be obtained within a short period of time.
On the other hand, in the case of synthesizing peptide by means of biotechnology, a minute controlling of enzyme reaction is required, thereby making it difficult to obtain various kinds of peptide in large quantity and cheaply.
In the meantime, hydroxyapatite is now noticed as a tissue affinity material. This hydroxyapatite has been conventionally manufactured mainly by means of wet chemical synthesis. There have been proposed various wet processes for manufacturing the hydroxyapatite. For example, Japanese Patent Unexamined Publication H4-20971 teaches a method of synthesizing hydroxyapatite by dropping, with stirring, an aqueous phosphate solution into a slurry of calcium hydroxide in an inert gas atmosphere, wherein a biochemical buffer solution such as Tris buffer solution or Good's buffer solution is employed thereby to obtain a hydroxyapatite having a Ca/P ratio of 1.67 in theoretical composition ratio.
The hydroxyapatite chemically synthesized in this manner is however accompanied with a defect that it scarcely contains a small quantity of minerals which are inherently contained in the tissue, so that this chemically synthesized hydroxyapatite is not expected to be readily and effectively utilized by a living body. Therefore, when this chemically synthesized hydroxyapatite is employed for a medical purpose, e.g. as a filling material for a defective portion of bone, a problem of insufficient compatibility of the hydroxyapatite with the living body will be raised. Moreover, since a strict pH control is required in the chemical synthesis of the hydroxyapatite, it is difficult to mass-produce the hydroxyapatite, thus leading to an increase in manufacturing cost thereof.
More recently, there has been developed a technique to produce natural hydroxyapatite from the bone of pig or cattle in place of the aforementioned chemical synthesis means.
Namely, according to this recent technique, the bone of pig or cattle is caused to fluidize while being baked at a high temperature in a furnace, and then a gaseous water is sprayed onto the fluidized bone so as to remove the protein or fat that have been adhered to the fluidized bone. However, since the bone is baked at a high temperature in this method, the degree of crystallinity of the hydroxyapatite constituting the main component of the bone is caused to change, thereby deteriorating the absorbability of the hydroxyapatite to human body.
A method which is capable of overcoming the aforementioned problem has been also proposed (Japanese Patent Unexamined Publication H2-188415). According to this method, the bone charcoal or baked bone that has been derived from animal products is dissolved in an inorganic acid and then subjected to a fine filtration, the resultant filtrate being subsequently added with an alkali thereby to precipitate hydroxyapatite.
However, since the hydroxyapatite to be obtained by the aforementioned technique is produced by dissolving baked bone for instance using an acid and then precipitated using an alkali, the resultant hydroxyapatite is in defect of organic compounds such as protein, amino acid, peptide, etc. even though it contains minerals. As a result, this resultant hydroxyapatite is accompanied with the problems that it is poor in compatibility with human body as well as in absorbability to human body.
When these conventional hydroxyapatites are employed as a tooth-paste, the abrasive action thereof is too great so that it will cause a prominent gingival recession or abrasion of enamel of tooth, so that only a little quantity of these conventional hydroxyapatites could be employed as an abrasive in the tooth-paste. Further, since some of these conventional hydroxyapatites contain no mineral, the effect of the enzyme existing in saliva and having a capability of forming tooth to absorb the hydroxyapatite and to remedy the defective portion of enamel of tooth becomes very small.